Yeah lately there are many scams popping up on Craiglist like this. Its either some fairly priced GPU at MSRP or some "amazing deal" on some second hand GPU. Now I understand that most people don't want to overcharge people, however usually when people sell something they look at recent listings and usually put in a price somewhere there.
When someone prices something way too low it can mean a few things. First might mean its damaged. Second might mean they need to sell it quick just to get cash quick. Third reason could be that the GPU doesn't exist and its some type of Paypal or other scam.
If you want to confirm, ask the seller to provide a photo with some custom text, if they do provide it. Then chances are they own the GPU and aren't scamming. However I would be very careful either way.
One paypal scam they do is say we will send it to you by blank shipping and give you tracking.
the tracking will say label made but package not dropped off.
You have to get a refund and they got to use your 900 for eight- ten days.